Magnum Block Education

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MR4V

MR4V

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Hi All

We don't get many magnums here in OZ so I'm after some info.

Is there a difference between the early blocks and later ones? Been told that the oiling system is different.

Are LA heads just a bolt on option or is there machining work to be done?

I know there's an issues with mech fuel pumps due to cam and there's an after market option for that, is there anything else that doesn't make it an easy swap with an early LA and 727?

Cheers
 
This website is a very good read

http://www.magnumswap.com/using-la-parts-on-a-magnum/

I don't know what you mean "early and late" all magnums oil the same. You may be confusing LA with Magnum

There's an adapter made for the magnum cam to restore the fuel pump, and you can use the earlier LA timing cover

You cannot put LA heads on a Magnum, but you can (with the right parts) put mag heads on an LA

LA heads are shaft rockers, oiled up through the block and through the shafts

Mag heads are oiled through the lifters/ pushrods like a Chev / Ford "ball stud" rockers
 
Thanks 67dart273. Link is very helpful. As in the

As it said in the link "Some rare, early Magnum blocks are machined with oiling passages for the LA style heads"
How do I tell if it's an early block with the LA style oil passages? Is it the as as an LA block and will it look different?
 
By early blocks, they are referring to the roller cam throttle body truck engines 88-91 I think. They may have put them is a few z body cars as well but not sure as I have no love or use for them. These had small heads that I think were pedestal rocker but not too sure. Block is somewhat desirable to LA guys because they can use LA heads but get roller and better pistons.

It would only have the oil hole if it was a TB engine. never seen a mpfi magnum with oil hole. If you want to check, put an LA head gasket on the Mag block and look at the oil passage hole in gasket....no hole, dont use LA heads. You will also need a custom length pushrod if you do use them.
 
MR4V said:
Thanks 67dart273. Link is very helpful. As in the

As it said in the link "Some rare, early Magnum blocks are machined with oiling passages for the LA style heads"
How do I tell if it's an early block with the LA style oil passages? Is it the as as an LA block and will it look different?
Click to expand...

Yeah, you are probably referring to what we call an "LA roller" block. These were before magnums, but had factory roller cams. they have the tapped holes in the valley for the roller lifters. I have one of these, it came with an interesting timing cover.....looks just like an LA, with V belts, but the fuel pump mount is still there but has a factory "plug" in the hole. It appears you could cut the plug out, tap the mounting holes and use the cover for a pump

So LA roller block has roller lifters, but still has the oil hole up through the block. If in doubt you can stick a thin rod (coat hanger etc) down the hole and it should come out the cam bearing
 
The Magnum blocks also have a shorter deck height.
 
67Dart273 said:
Yeah, you are probably referring to what we call an "LA roller" block. These were before magnums, but had factory roller cams. they have the tapped holes in the valley for the roller lifters. I have one of these, it came with an interesting timing cover.....looks just like an LA, with V belts, but the fuel pump mount is still there but has a factory "plug" in the hole. It appears you could cut the plug out, tap the mounting holes and use the cover for a pump

So LA roller block has roller lifters, but still has the oil hole up through the block. If in doubt you can stick a thin rod (coat hanger etc) down the hole and it should come out the cam bearing
Click to expand...

Thanks I'll try the coat hanger to see.
 
They did make a few magnums that oiled both ways, I had a couple of 92 and 93 models that had the oil hole for the LA heads.
 
hemichuck said:
They did make a few magnums that oiled both ways, I had a couple of 92 and 93 models that had the oil hole for the LA heads.
Click to expand...
They should have really been oiling through the pushrods whether they had the block passages or not.

magnummopar said:
By early blocks, they are referring to the roller cam throttle body truck engines 88-91 I think. They may have put them is a few z body cars as well but not sure as I have no love or use for them. These had small heads that I think were pedestal rocker but not too sure. Block is somewhat desirable to LA guys because they can use LA heads but get roller and better pistons.

It would only have the oil hole if it was a TB engine. never seen a mpfi magnum with oil hole. If you want to check, put an LA head gasket on the Mag block and look at the oil passage hole in gasket....no hole, dont use LA heads. You will also need a custom length pushrod if you do use them.
Click to expand...
Just Rams and vans. Some have mentioned not having to drill Mag blocks out for the LA oil holes.

67Dart273 said:
Yeah, you are probably referring to what we call an "LA roller" block. These were before magnums, but had factory roller cams. they have the tapped holes in the valley for the roller lifters. I have one of these, it came with an interesting timing cover.....looks just like an LA, with V belts, but the fuel pump mount is still there but has a factory "plug" in the hole. It appears you could cut the plug out, tap the mounting holes and use the cover for a pump

So LA roller block has roller lifters, but still has the oil hole up through the block. If in doubt you can stick a thin rod (coat hanger etc) down the hole and it should come out the cam bearing
Click to expand...
All TBI motors are roller blocks, 360s that are not TBI ('88-down) are not roller blocks. First year for 318 roller blocks was sometime early in the '85 model year- so there are '84 roller block 318s. These have the provisions for the roller cam retainers in the lifter gallery. Not all roller block 318s have roller cams- cop cars and carbed trucks didn't usually get roller cams.
 
67Dart273 said:
Also found this on wiki

https://en.wikipedia.org/wiki/Chrysler_LA_engine#Magnum_engines

"The easiest way to differentiate a bare Magnum block from a LA is by checking for the presence of the two crankshaft position sensor mounting bosses on the right rear top of the block, just to the rear of the cylinder head deck surface. Bosses = Magnum."
Click to expand...

In the vehicle just look for two sets of motor mounting points, "ears like LA" and "pads for mag trucks/vans"

Also keep in mind the truck pads will need ground down to clear most headers for cars.
 
Very helpful post. I just acquired a magnum 360 with the intention of tossing the potentially cracked mag heads and using a set of J Heads with an LD340 intake I have on the shelf. The next day buyers guilt set in as I read nothing but doom and gloom on the possibility of my J Heads not working unless the oil passages where drilled. After reading this post I checked the Mag block with the LA head gasket, every hole lined up and I verified the oil hole was clear through. I'm planning to top the heads with a set of Crane roller rockers. I believe I'll need to order a special push rod for this application. Again great post, glad I found it. Thanks FABO
 
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